Our TG-2 finish is a very durable finish but it has limitations that our TG-1 finish does not have. It's not nearly as heat resistant nor is it as resistant to chemicals. We beat the low chemical resistance issues by applying the powder coat under the Gunkote 2400 Series resin. (Zinc Parkerizing, then powder coat, then Gunkote) The Gunkote 2400 Series resin pretty much doesn't care what chemicals you expose it too...as long as you clean it afterwards. In other words: If you lay a warm rifle down on a glacier and then find that it has melted into the ice and gotten seriously frozen stuck, it's ok to drain a little fuel from the planes tank to melt the ice away as long as you rinse it off with water afterwards. The stocks finish may be ruined but the Tuff-Gun finish on the metal won't be affected. (Yes! It happened!!!)
However, there are major clearance problems and heat resistance issues with TG-
2. It's thicker and will cause interference issues with close tolerance moving parts. It will not burnish. It will change color and texture with exposure to high heat. Yes, there are powders that are for high heat. They're even thicker than the "normal" powders. Numbers and letters blurred by the finish are for rookies.
We offer our TG-2 finish with limitations. Bolt action rifle bolt handles, certain bipod legs, floor plates, etc. Things that don't fit tight, move, get super hot and are not exposed to "tension shock". That's what I call it but I'm sure it has a really scientific name. It's what happens to metal during the actual fired shot. It expands, stretches, twists, etc. I would not use powder coat on a .300 Magnum muzzle brake but it's fine on a .22 caliber. A super etxra heavy really hard finish is not good for metal that is subjected to stress. The finish can crack and shatter. A more flexible finish is able to move around some.
Regarding heat retention: Absolutely! Some finishes are designed to conduct heat. The Gunkote that we use is one of those. It conducts heat and that helps to eliminate hot spots. I use it on my model race boats engines. Those things get HOT!
http://www.shootiniron.com/BOAT.html
However, anything that is added to the metal surface can also act as insulation and increase heat retention....like powder coat. On a car's exhaust system, it's fine to retain heat. In fact, the system will work better because the gasses flow better and faster when hot. That's what "header wrap" is for. On a firearm, it's not so good. A powder coated firearm will run hotter because the powder acts as an insulator. Hope this helps. Keep yer powder dry, Mac. (It's not a pun, it's my signature)
Tuff-Gun Finishes. The Name Says It All.
Mac's Shootin' Irons
http://www.shootiniron.com